Rotary hook with thread and needle guard for sewing machines



L. J. KUHAR 3,151,589

ROTARY HOOK WITH THREAD AND NEEDLE GUARD FOR SEWING MACHINES Oct. 6, 1964 Filed Jan. 29, 1962 W m M J QLWIW. mm d fl- H u M 7 A F i m M ATT ENEY United States Patent 3,151,589 ROTARY HOOK WITH THREAE) AND NEEDLE GUARD Ft'R SEWING MACHINES Ludwig J. Kultar, Clark, NJ, assignor to The Singer Company, a corporation of l lew Jersey Filed .ian. 29, 1962, Ser. No. 169,390 3 Claims. (Cl. 112-228) The present invention relates to a rotm' hook for sewing machines and has for an object to provide an improved needle guard for a rotary hook.

The present invention is a further development of the invention forming the subjed matter of the co-pending United States patent application of Ketterer, Serial No. 169,412 filed January 29, 1962, now Patent No. 3,120,- 204. In accordance with this invention, the usual thread guard on the periphery of a rotary hook for a high speed industrial lock stitch machine, for example as disclosed in the United States patent of Kessler No. 2,085,699, is formed to extend in the direction of rotation of the hook forwardly of the loop seizing beak, and this forwardly extending portion is provided with a needle guard that is adapted to engage the needle and to hold the same out of the path of the loop seizing beak. In this manner there has been provided a rotary needle guard for a rotary hook that is simple, economical, and effective.

Having in mind the above and other objects that will be evident from an understanding of this disclosure, the invention comprises the devices, combinations and arrangements of parts as illustrated in the presently preferred embodiment of the invention which is hereinafter set forth in such detail as to enable those skilled in the art readily to understand the function, operation, construction and advantages of it when read in conjunction with the accompanying drawings in which:

FIG. 1 is a fragmentary perspective view of a sewing machine rotary hook embodying the present invention.

FIG. 2 is a fragmentary elevational view of the rotary hook illustrated in FIG. 1.

FIG. 3 is a fragmentary sectional view taken substantially on the line 33 of FIG. 2.

FIG. 4 is a fragmentary sectional view taken substantially on the line 44 of FIG. 3.

With reference to the drawings, there is illustrated a sewing machine throat plate 1 which is on the sewing machine bed and the upper surface of which constitutes a part of the work supporting surface of the machine. The throat plate 1 has a needle aperture 2 through which a reciprocatory needle 3 moves endwise and defines the point of stitch formation. A needle thread T is threaded through an eye 4 of the needle 3. Beneath the throat plate 1 is a hook shaft 5 on the end of which is mounted a rotary hook 5 that cooperates with the needle 3 in the formation of lock stitches. The hook 6, which is generally of conventional configuration, includes a cup shaped hook body 7 and a hub 8 that receives and is secured by set screws 9 to the hook shaft 5. The hook body 7 is formed with a loop seizing beak 10 that terminates in a loop seizing point 11. Upon rotation of the hook shaft 5, the hook 6 is rotated about the axis of the shaft 5 and the loop seizing point 11 moves in a counterclockwise circular path of travel defining a plane normal to the axis of the hook shaft 5. The needle 3 defines a needle path relatively to the hook 6 and the hook 6 is arranged on one side of and closely adjacent to the plane defined by the path of travel of the loop seizing point with the loop seizing point passing in loop se zing relation to the needle.

The hook body 7 has an internal circular raceway 12 in which is ionrnaled a peripheral bearing rib 13 of a bobbin case carrier 14. For assembly, a portion of the 3,151,589 Patented Oct. 6, 1964 raceway 12 in front of the loop seizing point 11 in the direction of rotation is open-sided and is closed by a gib 15 on the periphery of the hook body 7. The bobbin carrier 1 is held against rotation with the hook body 7 by a rotation restraining finger 17.

Mounted on the periphery of the hook body 7 by screws 18 is a thread guard 19. The thread guard 19 is formed of sheet material and includes a leading end 20 overhanging the loop expanding edge 21 of the beak 10. The end 29 is extended beyond the beak 10 in the direction of rotation of the hook and terminates in a free end 22 that rests upon the outer surface of the gib 15, thus completely spanning the gap in the hook body that is produced by the formation of the beak 14].

The thread guard 19 has a front edge 23, which is the free edge thereof on the side adjacent to the needle 3. In the area about the beak It the edge 23 is disposed rearwardly of the beak 10 to expose the same. In front of the beak 16, there is formed on the end 20 a tongue 24 that extends from the edge 23 toward the beak 18. The tongue 24 is sloped radially inwardly of the hook 6 from the edge 23 toward the free end. The edge of the tongue 2d constitutes a needle guard and comprises a needle deflecting surface 25 rising smoothly from the edge 23 and leading into a needle positioning surface 26 which is disposed immediately adjacent the point 11 of the beak 19 angularly of the hook, thus acting to position the needle at loop seizure to prevent collision between the point 11 and the needle 3, and is disposed beneath the point 11 radially of the hook so as to engage the eedle as closely as possible to the eye thereof without pinching the thread. Axially of the hook, the surface 26 is disposed substantially in the plane defined by the path of travel of the point 11. On the edge adjacent to the beak it), the tongue 24 is formed with a loop controlling tail 27 that receives the loop at cast-off and controls the same as it is withdrawn from the hook.

Numerous alterations of the structure herein disclosed will suggest themselves to those skilled in the art. However, it is to be understood that the present disclosure relates to a preferred embodiment of my invention which is for purposes of illustration only and not to be construed as a limitation of the invention. All such modifications which do not depart from the spirit of the invention are 'mtended to be included within the scope of the appended claims.

Having thus set forth the nature of this invention, what I claim herein is:

1. In a rotary hook for sewing machines, a hook body formed with a loop seizing beak terminating in a loop seizing point having a circular path of travel in a plane normal to the axis of rotation of said hook, said hook body being adapted to be arranged on one side of and with said loop seizing point in loop seizing relation to a needle, a thread guard secured to the periphery of said hook body behind said beak in the direction of rotation of said hook and having a leading end overhanging and extending forwardly of said beak in the direction of rotation of said hook, and a needle guard on the leading end of said thread guard in front of said seizing point and extendin therefrom in a direction axially of the hook toward said path of travel, said needle guard comprising a needle positioning surface disposed substantially in the plane defined by the path of travel of said loop seizing point and being located inwardly of said point radially of said hook and adjacent to said point angularly with respect to the axis of said hook, said needle guard being adapted to engage a needle and to position the same relaively to said loop seizing point to avoid collision of said point and needle at loop seizure.

2. in a rotary hook for sewing machines, a hook body formed with a loop seizing beak terminating in a loop seizing point having a circular path of travel, in a plane normal to the axis of rotation of said hook, said hook body being adapted to be arranged on one side of and with said loop seizing point in loop seizing'relation to a needle, a thread guard secured to the periphery of said hook body behind said beak in the direction of rotation of said hook and having a leading end overhanging and extending forwardly of said beak in the direction of rotation of said hook, said thread guard having a front edge on the side adjacent to the needle and disposed rearwardly of said beak to expose the same, a tongue extending from the leading end of said thread guard in front of said loop seizing point'toward said plane defined by the path of travel of said loop seizing point, said tongue having an edge constituting a needle guard and including a needle positioning surface and a needle deflecting surface rising smoothly from said needle guard front edge to said needle positioning surface, said needle positioning surface being disposed substantially in the plane defined by the path of travel of said loop seizing point and being located inwardly of said point radially of said hook andadjacent to said point angularly of said hook, said needle guard being adapted to engage a needle and to position the same relatively to said loop seizing point to avoid c0lli-' sion of said point at loop seizure.

3. A rotary hook for sewing machines in accordance with claim 2 in which said thread guard is formed of sheet material and said tongue is an integral part ofsaid thread guard.

References Cited in the file of this patent UNITED STATES PATENTS 2,019,284 Wesson Oct. 29, 1935 7 2,102,954 'Hohrnann Dec. 21, 1937 2,435,358 Kessler Feb. 3, 1948 

1. IN A ROTARY HOOK FOR SEWING MACHINES, A HOOK BODY FORMED WITH A LOOP SEIZING BEAK TERMINATING IN A LOOP SEIZING POINT HAVING A CIRCULAR PATH OF TRAVEL IN A PLANE NORMAL TO THE AXIS OF ROTATION OF SAID HOOK, SAID HOOK BODY BEING ADAPTED TO BE ARRANGED ON ONE SIDE OF AND WITH SAID LOOP SEIZING POINT IN LOOP SEIZING RELATION TO A NEEDLE, A THREAD GUARD SECURED TO THE PERIPHERY OF SAID HOOK BODY BEHIND SAID BEAK IN THE DIRECTION OF ROTATION OF SAID HOOK AND HAVING A LEADING END OVERHANGING AND EXTENDING FORWARDLY OF SAID BEAK IN THE DIRECTION OF ROTATION OF SAID HOOK, AND A NEEDLE GUARD ON THE LEADING END OF SAID THREAD GUARD IN FRONT OF SAID SEIZING POINT AND EXTENDING THEREFROM IN A DIRECTION AXIALLY OF THE HOOK TOWARD SAID PATH OF TRAVEL, SAID NEEDLE GUARD COMPRISING 